1. Field of the Invention
The present general inventive concept relates to a battery module, a computer system and a power supply method thereof, and more particularly, to a battery module which supplies an external power, and a computer system and a power supply method thereof.
2. Description of the Related Art
A portable computer, such as a notebook computer and a personal digital assistant (PDA), becomes popular due to its portability. Such a portable computer may use an external power through an AC/DC adaptor. Also, the portable computer uses a secondary battery which is recharged through the adaptor.
An extended battery life (EBL) technique has been used to extend a battery life span, among various techniques related to batteries of the portable computer. Thus, a narrow voltage direct current (NVDC) technique has been suggested as one of the battery-related techniques. The NVDC technique reduces a voltage range of a voltage direct current (VDC) inputted to a DC/DC converter which converts power from an adapter or battery into power within a voltage range to drive respective components of the portable computer.
The portable computer which employs the NVDC technique may have a power supply in which an adaptor and a battery are formed as a single body. As illustrated in FIG. 1, the power supply supplies power Vdc in different ranges to a system part 1 through a switch, by receiving a voltage of Vdc1 from an external adaptor or a voltage Vdc2 from an adapter of a battery module 2, and by receiving a voltage of 9V to 12.6V from a battery of the battery module 2.
However, the external adapter and the integrated battery module 2 require an additional cable which is exposed to an outside thereof, to supply power to the system part 1. Since, the portable computer is supplied with a first external power from the adapter of the battery module 2, a second external power additionally from the outside or an auxiliary power from the battery, it needs several switches to prevent a short-circuit due to potential differences among the first external power, the second external power, and the auxiliary power supplied from the battery. Then, the power connection becomes complicated, thereby causing inconvenience in carrying the portable computer and the risks of the short-circuit.